NMTC/JAM is an upgraded version of the code system NMTC/JAERI97.
NMTC/JAERI97 simulates high energy nuclear reactions and nucleon-meson transport processes. It implements an intranuclear cascade model taking account of the in-medium nuclear effects and the preequilibrium calculation model based on the exciton one. For treating the nucleon transport process, the nucleon-nucleus cross sections are revised to those derived by the systematics of Pearlstein. Moreover, the level density parameter derived by Ignatyuk is included as a new option for particle evaporation calculation. A geometry package based on the Combinatorial Geometry with multi-array system and the importance sampling technique is implemented in the code. Tally function is also employed for obtaining such physical quantities as neutron energy spectra, heat deposition and nuclide yield without editing a history file.

The code can simulate both the primary spallation reaction and the secondary particle transport in the intermediate energy region from 20 MeV to 3.5 GeV by the use of the Monte Carlo technique. The code has been employed in combination with the neutron-photon transport codes available to the energy region below 20 MeV for neutronics calculation of accelerator-based subcritical reactors, analyses of thick target spallation experimented and so on.

High energy nuclear reactions induced by incident high energy protons, neutrons and pions are simulated with the Monte Carlo Method by the intra-nuclear nucleon-nucleon reaction probabilities based on an intranuclear nucleon cascade model followed by the particle evaporation including high energy fission process. Jet-Aa Microscopic transport model (JAM) is employed to simulate high energy nuclear reactions in the energy range of GeV. All reaction channels are taken into account in the JAM calculation. An intranuclear cascade model (ISOBAR code) taking account of the in-medium nuclear effects and the preequilibrium calculation model based on the exciton one are also implemented for simulating the nuclear reactions. Inter-nuclear transport processes of the incident and secondary nucleons in macroscopic material regions are simulated with the Monte Carlo method based on the O5R algorithm and a continuous slowing down model for charged particles using the nucleon-nucleus cross sections based on the systematics of Pearlstein.

In case of the sample problem of 50 GeV protons on 50 cm diameter by 30 cm long Pb target, it takes about 3 hours for 5,000 proton incidence, or about 2 sec per history, on the Dec alpha 600 MHz (OS: Linux). The running time varies depending upon the target size and the incident beam energy.

A geometry package based on the Combinatorial Geometry with multi-array system (MARS) is used for defining the geometry model of a problem. The importance sampling technique is implemented in the code to simulate the particle transport process effectively. Tally function is also employed for obtaining such physical quantities as neutron energy spectra, heat deposition and nuclide yield without editing a history file. The array size required for geometry model and tally is adjustable by changing the parameter size in an include file.

The transport of neutrons with energies below cut-off energy (20 MeV) has to be calculated independently by the neutron-photon transport code such as MCNP using a cross section library processed from evaluated nuclear data.

Between 10 and 11 Mb of memory are necessary.
Several hundreds of mega-bytes to giga-bytes storage for cut-off neutron history storage.
The memory and storage capacity is determined depending upon the parameter values and target size of problems.